What is Ketosis and How Does it Work?

On traditional diets, your body primarily runs on energy from sugars —or more technically speaking, glucose. Carbs are your preferred source of this type of fuel since many carbs are made up of glucose and they can be quickly broken down into fast energy. But protein and fats can also supply small amounts of glucose through a process called gluconeogenesis. It is just a much slower process.

By restricting carb intake to very low levels (less than 50 grams per day), you can drastically alter the way your body finds energy. Essentially, without enough carbs to get glucose quickly, your body has to rely on an alternative source: fat!

On any diet, even high carb diets, your body uses some amount of fat for fuel—mainly at rest and in between meals. But this is typically a slow process and fat is not the main source of energy overall. In addition, fatty acids are not a desirable source of energy for your brain.

So what happens when you restrict carbs for long periods of time?

Without enough carbs for glucose, your liver produces ketones from fatty acids that can be used by your brain and can supply a quicker, more steady stream of energy to your body. This is the process of ketogenesis, resulting from a ketogenic or “keto” diet. And when ketogenesis takes over (officially switching from sugar to fatty acids as your main source of energy), you enter the metabolic state called ketosis.

Ketone Bodies

While ketosis is unique to the ketogenic diet, ketone bodies are not. Ketones are produced normally during periods of starvation, fasting or prolonged exercise. A keto diet differs in that ketone production is prolonged and increased, becoming the primary source of fuel for your muscles and brain, over anything else.

For example, ketone bodies supply less than 6% of your body's energy requirements after an overnight fast (or normal sleep patterns) but jump to 30 to 40% of your fuel after a 3‐day fast, and this increases to more than 60% during ketosis (1).

Your liver produces three types of ketones or ketone bodies:

Acetoacetate

Beta-hydroxybutyrate (BHB)

Acetone

Acetoacetate is the main ketone produced by the liver during fatty acid metabolism or during restricted carbohydrate intake. It is then further converted into either BHB or acetone. Some acetoacetate is used for energy and any excess is excreted through urine—this is the ketone that urine-based keto test strips look for!

BHB is the main ketone used for fuel by your muscles and organs during ketosis, and it is the ketone body that is able to supply your brain with energy in the absence of glucose. Reaching higher BHB levels is a key desired result of ketosis.

Acetone is not as stable as the other types of ketones, so it is not the primary ketone used by the body and is only produced in small quantities. And since it is excreted when you exhale, it's acetone that's responsible for the fruity breath (keto breath) some claim to experience in ketosis.

Health Benefits of Ketosis

There are a number of health claims out there around a ketogenic diet—including that it can cure cancer, reverse diabetes, and prevent Alzheimer's. But not all of these claims are backed by research, and most of the science surrounding keto for weight loss and a number of health conditions is still in its early stages.

But there are some possible health advantages to ketosis that are worth noting.

Ketosis Improves Insulin Sensitivity

Insulin is the hormone that regulates blood sugar control by delivering sugars to your cells as a source of usable energy and storage. The better your body responds to insulin (insulin sensitivity), the more efficiently it works. And for many with diabetes or those at risk for developing diabetes, insulin resistance (poor insulin sensitivity) can cause a host of health problems.

While more research is needed, there are a few promising studies suggesting that a keto diet may help improve insulin function more than other calorie controlled diets (2,3,4).

In one study, participants followed a keto diet for 10 weeks and saw their HbA1C (marker for long-term blood sugar control) drop significantly, with half seeing their levels return to normal (5).

Ketosis Might Improve Cholesterol

Contrary to what one might initially think about a high-fat diet, especially one that is typically high in animal-based fats and high sodium foods, a ketogenic diet seems to have a positive effect on blood cholesterol (6,7).

However, it is not clear whether these results are from weight loss on a keto diet or directly attributed to ketosis.

Ketosis for Weight Loss

Creating a calorie deficit is the most widely accepted approach to losing weight. However, there are quite a few theories regarding ketosis as an approach to faster weight loss, even outside of calorie control. The research has yet to prove any of these theories, but they offer an interesting point of debate.

Here are three ways ketosis may help speed up your weight loss efforts:

1. Increased Metabolism

The process of using fat for fuel rather than carbs may cause the body to work harder, and therefore burn more calories digesting food. Your resting metabolic rate (RMR) may also increase on a low carb diet—up to 4% (8). This is different from what we know about other diets that cause your metabolism to slow down, making weight loss harder.

However, this process may be more efficient when protein intake is higher—roughly 30% of your calories—since protein is the most thermogenic macro and fat is thermoneutral. And multiple studies have suggested high protein diets may positively influence metabolism, whereas fat alone has not been shown to do this.

2. Increased Fat Burning

Ketosis allows you to become more efficient at burning fat for fuel, making you a fat burning machine! And it may help promote more fat loss overall (9).

However, this is yet to be proven in well done human studies.

So far, the research has shown us that using stored fat for energy will probably only translate into weight loss when calories are restricted. If your calorie intake exceeds your needs, you will still continue to store fat regardless of how much fat you are breaking down for energy—and you can actually gain weight in the process.

3. Decreased Appetite

It might not just be the type of food you are consuming on a keto diet that is helping to curb your appetite. In one study, Ketosis was thought to contribute to lower levels of ghrelin, a hormone responsible for increasing your hunger (10).

Although more research is needed, this hormonal response, in combination with the satiating effect of keto foods, could be an important factor in promoting more weight loss and helping you cut more calories overall on a keto diet.

Ketosis vs Ketoacidosis

Ketosis resulting from a ketogenic diet is thought to be relatively safe in many people, as it is a natural phenomenon that occurs in various stages of life as a protective measure when carbs are not readily available. In fact, babies, young children, and pregnant women are able to quickly enter ketosis after short periods without food or carbohydrates (11).

However, ketosis is often confused with ketoacidosis, a dangerous condition that can occur in diabetics. This might be some of the reason why some people claim a keto diet isn’t healthy.

Ketoacidosis is considered to be a form of ketosis, but the cause differs significantly from a typical diet-induced ketotic state. Ketoacidosis is most common in type 1 diabetics because of their need for insulin. When insulin medication isn't taken properly, ketone levels can rise to dangerous levels, leading to ketoacidosis. Other frequent triggers include infections and other major stressors on the body such as heart attacks.

How to Get Into Ketosis Fast

There are really two main ways to get into ketosis through diet.

Fasting for an extended period of time

Cutting your carb intake

While starvation is one way, it’s not exactly a sustainable option for weight loss.

The traditional keto diet plan designed to push you into ketosis involves altering your keto macro balance towards high fat, moderate protein and very low carbohydrate. This provides an abundance of fat and very little accessible glucose.

How Many Carbs for Ketosis?

The amount of carbs you should consume to promote ketosis can differ from one person to the next and can range from less than 20 grams to as high as 70 to 100 grams of carbs per day for very active individuals.

Your carb needs for ketosis depend on the following:

Overall calorie needs

Fitness level

Body composition (% body fat)

By general rule of thumb, you can assume roughly 5% or less of your calories should come from carbs, which equals around 20 grams of carbs per day for most. But if your calorie needs are higher or you are extremely active, you might want to consider starting at 50 grams of carbs or higher.

And keep in mind that your total carb intake for ketosis is based on net carb intake. Meaning fiber, which is also a carb, can help cancel out some of the total carbs you eat. In other words, if you eat 30 grams of carbs a day but 10 grams of it comes from fiber, your net carbs intake is still 20 grams.

How Much Protein on Keto?

A traditional keto diet suggests a limited to moderate amount of protein intake. This is because protein can be converted into glucose through gluconeogenesis and this may interfere with your ability to stay in ketosis. But gluconeogenesis is not detrimental to ketosis, as your body will always require some amount of glucose to keep blood sugar levels normal and supply energy to parts of the body that cannot use ketones—like your blood cells and parts of your brain.

There are a number of benefits to including more protein on a keto diet:

Protein is satiating and supports healthy weight loss

Protein protects your muscle mass

High protein intake has long been associated with weight loss due to its ability to slightly increase metabolism during digestion (it is the most thermogenic macro) and it is thought to be incredibly satiating (12,13).

Protein is also an essential building block for your entire body, including your lean tissue. If you aren't getting enough protein through diet, you will start to break down muscle mass to get it. This could cause you to lose strength and muscle on a low protein keto diet.

The most precise way to determine how many grams of protein you should eat a day is to base it on your lean body mass—you should strive to get 1 gram of protein per pound of lean tissue. You can also calculate your needs based on your total body weight and fitness goals. Or you can roughly determine how many grams of protein you should eat each day based on your calorie needs, aiming to get 20 to 30% of your calories from protein.

If you are just getting started on a keto diet, you might want to consider keeping protein intake lower at first to assist in getting you into ketosis quickly, and then add additional protein after a week or so.

How Many Grams of Fat on Keto?

Eating higher fat alone is not going to promote ketosis—rather, it's the restriction of carb intake that does it. Including higher fat in your diet is a way to provide your body with a consistent source of fuel that it can use to generate ketone bodies and sustain bodily functions.

The easiest way to determine how many grams of fat you need on a keto diet is to calculate your carb and protein needs first and then allocate the remaining calories to dietary fat—and then divide by nine to get grams of fat per day. For example, if you need 2,000 calories a day, with 20 grams of carbs (20 grams x 4 calories per gram = 80 calories from carbs) and 100 grams of protein (100 grams x 4 calories per gram = 400 calories from carbs), your remaining calories would be:

2,000 - (80 +400) = 1,520

And this would equal roughly 169 grams of fat per day.

1,520 / 9 = 169 grams of fat

Medium Chain Triglycerides (MCT)

Are some fats better than others when it comes to a keto diet?

Unsaturated fats from plant-based sources have long been touted as the best sources of healthy fats and should be prioritized on any diet, including keto. But when it comes to ketosis, a certain type of saturated fat called MCT (medium chain triglycerides) may offer additional benefits.

MCTs comes from plant-based saturated fats like coconut and palm oil, as well as grass-fed dairy sources like goat milk, cheese, yogurt, kefir, butter, and ghee. You can also purchase MCT oil supplements.

Unlike other fatty acids, MCTs do not require additional compounds to be digested and utilized for energy (14,15). Similar to how carbohydrates can be an immediate source of glucose, MCTs can be quickly absorbed and turned into ketones for fuel. And unlike carbs, MCTs do not affect blood sugar levels.

Their ability to form a rapid source of ketone bodies is ideal for someone on a ketogenic diet, especially during times when fast energy is needed—like during physical activity or exercise (15,16). Their rate of absorption may also aid in speeding up ketosis by promoting more ketone body formation.

Intermittent Fasting

Fasting for 24 hours for up to 3 three days is another way to get into ketosis quickly. However, this practice is not only difficult but unsustainable long-term.

Intermittent fasting or fasting for shorter windows is often discussed as an option to promote faster ketosis and strengthen the overall benefits of a keto diet (17). It would make sense in theory that not eating for extended periods of time would help deplete glycogen stores, reduce overall carb intake and promote more fat utilization for energy, but this all really depends on what your overall diet looks like.

Similar to most other diets, intermittentfasting is effective as another way to organize your calories to promote an overall caloric deficit. And with any fasting pattern, a deficit is only created when food choices are kept in control—not eating for fourteen hours is a not a license to eat as much of whatever you want for your 10-hour window. Especially if you are trying to stay in ketosis!

But still, fasting may be the best method for some who have a hard time controlling their intake. At the end of the day, the best diet for you is one that you can stick to! And with a focus on quality, nutritious foods, and calorie control, many may find that intermittentfasting is just what they need to manage their weight, appetite and blood sugar levels.

Exercise

Exercise can also help put you into ketosis more quickly by using up available glucose stores. Prolonged exercise or more slow-paced endurance sports (like cycling, swimming, jogging, etc.) also force you to switch to fat as a primary source of fuel, which can further support a ketotic state (18).

But not all types of exercise are sustainable without carbs. If you are participating in heavy training, high-intensity conditioning or heavy lifting throughout the week, you might need to add some additional carbs to maintain your strength and output.

If you are an athlete or very physically active, consider adding some additional carbs (15 to 30 grams) before HIIT or heavy strength training to support your energy needs.

Exogenous Ketones

Some research suggests that ketone supplements can also increase the rate at which you go into ketosis and create a ketotic state even without following a ketogenic diet (19). However, this approach is thought to be beneficial when MCTs are included.

Of course, this approach should not be a permanent substitute for a well-rounded keto diet. It is the actual act of diet-induced ketosis and carb restriction that many pro keto individuals claim is beneficial to this unique style of dieting (20,21,22).

But if you are looking to increase your level of ketones to promote ketosis quickly, a ketone supplement paired with MCT oil may be worth considering.

How Long Does it Take to Get Into Ketosis?

The rate at which you can get into ketosis depends on your activity level, body type, and overall diet.

Cutting carbs for a day isn't going to flip the switch. Your body has been running off sugars your whole life and needs time to adjust. Part of this process requires you to deplete your reserve of carb fuel (glycogen stores).

And the number of stored carbs you have can differ from one person to the next depending on how many carbs you typically eat each day and your overall muscle mass. You store these carbs in your muscles, so more muscle means more storage! Your level of physical activity also plays a role—the more you are exercising, the quicker you will run out of glycogen.

In healthy individuals who have just started the ketogenic diet, it usually takes two days to burn through glycogen. But taking all of the individual variables into account, the time frame to get into ketosis is most often quoted between 1-7 days.

Signs of Ketosis (Symptoms)

Wondering if you've achieved ketosis? Here are a few things you can look for:

Keto Breath

As ketone body production increases, acetone is exhaled through your breath, producing a fruity sent. If you notice this slight change, it could be a sign of ketones taking over.

If the smell is bothering you, brush your teeth throughout the day or try sugar free mints and gum.

Decreased Appetite

If you're finding your cravings are fading and you can go a little longer between meals without as much hunger, you could be in ketosis. Although the mechanism behind this phenomenon is still being investigated, it is thought that fat supplies a more steady stream of energy than carbs and doesn't cause spikes in blood sugar. Keto foods are more satiating, and ketosis may suppress hunger hormones.

Increased Focus and Energy

While it is thought that starting a keto diet may result in a little brain fog from the "keto flu," settling into ketosis may actually help improve your mental clarity and focus. Although research is still in its early stages around ketosis and brain health, you may find that your memory is sharper and your mood is a little brighter while on a keto diet (23,24).

Ketone Test Strips

Of course, the most definitive way to determine whether or not you are in ketosis is to test your ketone levels! Commercial ketone test strips are available for both blood and urine. Although, these tests primarily look at levels of AcAc (not BHB) and cannot measure the exact amount of ketones in your blood. Regardless, they are a good indicator of whether or not you might be in ketosis, especially when coupled with other symptoms noted above.

Most sources recommend a goal of 0.5 to 3 mM for weight loss on the ketogenic diet. It isn't thought that there is a benefit to going over 3mM and these higher levels can represent a state of starvation for some people (meaning you aren't getting enough food)! The dangerous condition of ketoacidosis that occurs in diabetics often involves much higher levels of ketones, usually greater than 10 mM.

Ketone Level Chart

Normal Serum Levels

<0.5mM

Desired Levels for Ketosis

0.5 to 3 mM

Ketoacidosis

> 10 mM

*Chart represents common ketone levels, but these can vary based on multiple factors.

How to stay in Ketosis

The easiest way to stay in ketosis is to stick to your ketogenic diet and continue to keep carb intake low. Make sure you are tracking your daily macros using a macro tracking app, like Trifecta.

Keto Cheat Day

But what happens if you go off your diet? Is it possible to have cheat meals and still be successful on a keto diet?

Yes! It is possible to go in and out of ketosis safely. But how drastically and how often you cheat is certainly going to affect your progress in the long run, and you might end up undoing a lot of hard work if you aren't careful.

If you just couldn't resist that slice of cake or pasta dinner and chose to indulge on a few extra carbs, don't stress. This isn't a reason to throw your entire diet out the window. Depending on how many carbs you consumed, you might not even have pulled yourself out of ketosis. But on the contrary, if your cheat was over the top, it might take you a little while to switch back once you get back to your keto meal plan since it takes anywhere from 24 hours to a week to get into ketosis in the first place.

Of course, how long you've been keto and you ketone levels can have an impact on how much a splurge is going to affect you. If you have been on keto for more than 3 to 6 weeks, you are likely getting 70% of your energy from fat, and it will be much easier to go back into ketosis quickly, compared to someone who is not fully fat adapted.

Cheating around a time you are exercising can help keep you in ketosis since you are using up the extra carbs quickly. And supplementing with ketones and MCT oil may also help speed up the process.

Some may notice an intense sugar crash once they start eating carbs again. You might also notice some repeat symptoms of "keto flu" when resuming your diet.

And while ketosis is one thing, don't forget to track your calories. If your cheats are blowing your weekly calorie average out of the water, you might end up gaining weight.

If you're finding that you are cheating often and having a hard time sticking to your keto diet consistently, it might be time to revisit whether or not this diet is right for you. At the end of the day, the best diet is going to be one you can stick to!

Carb Refeed Day

Cheats are a little different than a planned carb refeed, in which carb intake is planned to replenish glycogen stores, calm cravings and boost leptin levels (26,27). And the research on refeeds for a keto diet is lacking, so it really depends on what works best for each individual. If you are happy on your keto diet and still getting results, a refeed is likely, not necessary.

Going Off a Keto Diet

There is also a lot of misinformation around going off a keto diet. Just because you start eating carbs again, doesn't mean you will store a bunch of body fat. A majority of the carbs you eat will likely be used to replenish glycogen stores. And while you may have a slight adjustment period with blood sugar levels and water retention, as long as you are maintaining calorie control, you shouldn't end up gaining any weight. If you are looking to go off your keto diet, cut back on fat intake slowly and reintroduce healthy carbs from fruits, veggies and whole grains over sugar.

Keto Diet Long Term

Unfortunately, there aren't really any long-term studies examining the success of a ketogenic diet for weight loss. Research suggests that keto works well for short term results, but we aren't sure about staying keto for the long haul. Not to mention, a really restrictive diet like keto puts you at a higher risk for nutritional deficiencies if you aren't choosing nutrient-dense foods and paying attention to your macro and micronutrient intakes.

If you are looking to stay in ketosis long term, make sure you are keeping good nutrition in mind and opt for a daily supplement if you find your diet is lacking in any vitamins or minerals. And always talk to your doctor about long term health and chronic disease prevention options.

Keto Diet Delivery

Whether you are looking to go into ketosis or just stick to your keto diet, consider using a meal delivery company that does all the hard work for you. Trifecta's keto meal plan will not only help you cut carbs, but it's loaded with nutrient-rich foods and healthy fats to keep your overall diet and nutrition on track.